There has been a strong commitment to population research in training at Johns Hopkins University for many years. Currently almost 50 faculty members in the department, ranging from the clinical and biological sciences to the social sciences, are engaged in population research. There remains a lack of communication between investigation and disciplines and also deficiencies in essential facilities. This proposal is to develop the Hopkins Population Center as an integrating and supporting resource in the University to strengthen and expand population research in both the biomedical and social science areas. Funds are requested for a directorate to provide overall coordination and for core support in seven areas. These are: 1) a population information unit including an information retrieval system and data archives; 2) data processing facilities; 3) mathematical and statistical services; 4) a field research facility in the Baltimore metropolitan area; 5) reproductive biology facilities including a hormone assay laboratory and electron microscopy; 6) clinical research facilities; and 7) a communications-publications unit. Two Program Development Proposals are included: 1) the development of electron microscopy capability to support several groups of investigators in reproductive biology; 2) the initiation of studies of population structure and social welfare in the Baltimore metropolitan area.